The present invention relates, in general, to an improved handle for surgical instruments and, more particularly, to an improved scissor type handle wherein the movable handle element is attached to the body of the instrument by a camming mechanisim including a first cam and a second cam.
U.S. Pat. No. 322,055 describes an ultrasonic surgical apparatus which includes a surgical instrument having a handpiece with a transducer for converting an electrical signal into longitudinal vibratory motion. The longitudinal vibratory motion is transmitted to an ultrasonic blade which is connected to the handpiece. An accessory is releasably connected to the handpiece to enable clamping of tissue against the vibrating blade to afford improved coagulating and cutting of tissue. In U.S. Pat. No. 5,322,055 Scissors-like grips actuate a pivoted clamp jaw along one side of the ultrasonically vibrating blade to compress and bias tissue against the blade in a direction which is substantially normal to the direction of longitudinal vibratory movement. In U.S. Pat. No. 5,322,055, the clamp jaw and blade are rotatable relative to one another to align a selected blade edge of a multi-edged blade with the clamp jaw for cutting and coagulating while clamping or circumferentially spacing a selected blade edge from the clamp jaw for cutting and coagulating without clamping. U.S. Pat. No. 5,322,055 is hereby incorporated herein by reference.
Many surgical instruments, such as the ultrasonic surgical device illustrated and descried in U.S. Pat. No. 5,322,055, use elements such as actuation rods to transmit force from the proximal end of the instrument, where the instrument is gripped by the surgeon, to the distal end of the instrument where the transmitted force is used to actuate an end effector such as, for example, a clamping jaw. In order to effectively transmit force from the surgeons hand to the end effector in such an instrument, it is necessary to translate the grasping motion of the surgeons fingers to the lateral motion of the actuation rod. Scissors type grips are used in many surgical devices of this kind because they are comfortable and tend to be familiar to the surgeon. Many such instruments use a single pivot pin in combination with a cam of some type to translate the arcuate motion of the scissor grip to the linear motion of the actuation rod. However, in certain circumstances, such an arrangement may not be acceptable, such as, for example, where the room in the instrument body is limited and rotational movement of the grip around a fixed pivot pin requires too much of the available room. Further, in order to increase the stroke in pivot pin arrangement, it is generally necessary to increase the distance from the pivot pin to the cam, requiring more room if a longer stroke is desired. It would, therefore, be advantageous to provide an improved actuation mechanism for translating the grasping motion of a human hand to the lateral motion necessary to drive an actuation rod. In particular, it would be advantageous to provide such an improved actuation mechanism without using a fixed pivot pin type arrangement. It would also be advantageous to provide such an improved actuation mechanism in an in line handle arrangement and to reduce the room necessary for the actuation mechanism without substantially reducing the stroke length of the actuation rod.
The present invention is directed to a surgical instrument such as, for example, an ultrasonic surgical cutting and coagulating device, wherein the gripping movement of the surgeon is mechanically translated into lateral movement to move, for example, an actuating rod. One embodiment of the present invention includes a camming pivot for use in surgical instruments, wherein the camming pivot includes: a lever arm; a first cam at a distal end of the lever arm; and a second cam positioned distally from the first cam. In one embodiment of the present invention, the first and second cams may comprise, for example, camming pivot pins moveable within first and second camming slots. In a further embodiment of the invention, the first camming slot may include a curved or angular interior camming surface.
In a further embodiment of the present invention, a surgical device includes an end effector, a camming pivot actuation mechanism and an actuation rod connecting the end effector to the actuation mechanism. In such an instrument, the actuation rod is gennerally positioned substantially parallel to the central axis of the instrument. The end effector may include, for example, an ultrasonic blade and a movable clamping element disposed opposite the ultrasonic blade. The actuation mechanism, which is operatively connected to the moveable clamping element by, for example, the actuation rod, may include a lever arm and first and second cams at a distal end of the lever arm. In this embodiment of the invention, the first cam may comprise, for example, a first camming pin positioned on the lever arm and a first camming slot operatively associated with the first camming pin where in the first camming slot is positioned at an angle to the central axis of the instrument. The second cam may comprise, for example, a second camming pin positioned on the lever arm distally from the first cam and a second camming slot operatively associated with the second camming pin, with the second camming slot being positioned substantially parallel to the central axis of the instrument.